The Abbott government has announced an “efficiency” review of the ABC and SBS as it looks for ways to save money.

The communications minister, Malcolm Turnbull, said the cost review would not examine either broadcaster’s charters or editorial or programming decisions.

The charter exclusion suggests the government is not rethinking the expansion of taxpayer-funded digital news services in competition with commercial outlets, which have increasingly introduced paywalls.

The review, to be conducted by the Department of Communications, will focus on the “efficiency of the operations” of the ABC and SBS. It will be assisted by Peter Lewis, a former Seven West Media chief financial officer.

The government provides the ABC and SBS with combined funding of about $1.4b each year, a bill that has previously attracted the ire of conservative critics.

Turnbull said it was a routine responsibility of the minister to ensure the ABC and SBS used public resources as efficiently as possible.

“Over time parliament has broadened the charter responsibilities of the ABC and SBS. But the means by which these responsibilities are delivered, resources are allocated and priorities determined is at the discretion of the national broadcasters’ boards and managements – with varying levels of transparency to the government of cost drivers or scope for efficiencies,” Turnbull said on Thursday.

Even before the announcement, Labor and the Greens were accusing the Abbott government of paving the way for ABC funding cuts.

Labor's communications spokesman, Jason Clare, said Tony Abbott told SBS News the day before the election there would be "no cuts to education, no cuts to health, no change to pensions, no change to the GST and no cuts to the ABC or SBS".

Turnbull said the study would examine the costs of the day-to-day operations that delivered ABC and SBS programs, products and services “and propose options to increase efficiency and reduce expense”.

“The objective is to ensure ABC and SBS fulfil their charter responsibilities at least cost to the community, and keep pace with rapidly changing practices in the broadcasting sector,” he said.

“It will not review the terms of the national broadcasters’ charters, or editorial and programming decisions. In other words, the study will not review the content of what is broadcast, but rather the cost of delivering that content and the operations that support it.”

The terms of reference indicate the review will look at ABC and SBS activities, such as television, radio, international services and digital services including online and catch-up TV.

It will also scrutinise production and facilities, SBS advertising, enterprises and retail services, corporate overheads, asset management and capital expenses.

Included in the review will be operational governance and management practices "including ways of enhancing the efficient and transparent management of the organisations".

But the terms of reference say the review will not look at changes to the ABC and SBS charters, editorial policies, allowing advertising on the ABC, or the quality of programs and products delivered by the broadcasters. It will also exclude a review of transmission costs, which will be dealt with in separate advice to the government.

Turnbull told the ABC the timing of the announcement was "completely coincidental" and had nothing to do with this week's debate about news balance.

He said he was aiming for a stronger and more resilient ABC and the review was not part of any "assault on the ABC".

"There is no more passionate defender of the ABC than me. I've said again and again that I believe that the ABC is a vitally important part of our nation's polity. It is is one of the great foundations of journalism and news gathering and broadcasting in the country. It has a very special place in Australia," he said.

Turnbull has asked for the study to consider the return on investment of the public funding, including in terms of audience and other usage. Ratings and audience reach will be examined. He has asked for a breakdown of costs in state and regions and by audience or user demographic. The review should quantify "the costs of operating at locations across Australia".

Turnbull stressed the study was being conducted “with the full co-operation and assistance of ABC and SBS”, saying both broadcasters had volunteered representatives to work on the team to be overseen by Lewis.

Turnbull referred to “last-century work practices” at the ABC during a discussion with colleagues at a Coalition party room meeting in early December. This appeared to be an indication that in future it may need to do more with less.

During that meeting, several MPs, including the South Australian Liberal senator Cory Bernardi, raised concern about the ABC. The discussion came amid controversy over the ABC’s decision to collaborate with Guardian Australia on the story that revealed Australian spy agencies’ past attempts to target the phone of the Indonesian president.

MPs noted their belief the ABC was in breach of its charter and was cannibalising the local media landscape. There were views expressed that the ABC had too many TV channels and took up significant taxpayer resources.

The Rupert Murdoch-owned News Corp has long raised concerns about the ABC expanding into digital news services. The ABC’s online content is offered free to readers and viewers, and News Corp is one of several publishers arguing the ongoing digital expansion threatens their business.

The efficiency study will start in February and is due to be completed by April.